If you have an allergy, your immune system overreacts to a substance you inhaled, touched or ate.

Your immune system controls how your body defends itself. For instance, if you have an allergy to pollen, your immune system identifies pollen as an invader or allergen. Your immune system overreacts by producing antibodies called Immunoglobulin E (IgE). These antibodies travel to cells that release chemicals, causing an allergic reaction. These reactions can range from annoying sneezing and sniffling to a life-threatening response called anaphylaxis.  

So how can you be sure which allergens are responsible for your symptoms? Allergy tests, combined with a physical examination and medical history, can give precise information about what you are, as well as what you are not, allergic to. For instance, perhaps you or a family member has allergy symptoms and your household includes a pet. You don’t have to avoid contact with the pet if allergy testing shows an allergy to dust mites but not to pet dander.

Many people with untreated allergy symptoms aren’t aware of how much better they will feel once their symptoms are properly diagnosed and managed by an allergist / immunologist, often referred to as an allergist.

An allergist is a pediatrician or internist with at least two additional years of specialized training in the diagnosis and treatment of allergies, asthma and immunologic disorders.  

When is Allergy Testing Appropriate?
Testing done by an allergist is generally safe and effective for adults and children of all ages. The allergen extracts or vaccines used in allergy tests performed by allergists meet U.S. Food and Drug Administration (FDA) requirements.

Symptoms which usually prompt an allergist to perform testing include:
• Respiratory: itchy eyes, nose or throat; nasal congestion, runny nose, watery eyes, chest congestion, cough or wheezing
• Skin: itchiness or eczema  
• Abdominal: vomiting or cramping and diarrhea consistently after eating certain foods
• Severe reactions to stinging insect stings (other than swelling at the site of the sting)
• Anaphylaxis (pronounced an-a-fi-LAK-sis): a serious allergic reaction that affects many parts of the body at the same time
It is important that allergy testing is directed by a healthcare professional with sufficient allergy/immunology training and prompted by your medical history.

Types of Allergy Tests
Different allergens bother different people, so your allergist will determine which test is the best for you. Regardless of the type of test, an allergist will first perform a physical examination and ask questions about your symptoms to determine if allergy testing is warranted.

IgE Skin Tests: This type of testing is the most common and is relatively painless. A very small amount of certain allergens is put into your skin by making a small indentation or “prick” on the surface of your skin.

If you have allergies, just a little swelling that looks and feels like a mosquito bite will occur where the allergen(s) to which you are allergic was introduced. If you are allergic to ragweed pollen but not to cats, only the ragweed allergen will cause a little swelling or itching. The spot where the cat allergen was applied will remain normal.

You don’t have to wait long to find out what is triggering your allergies. Reactions occur within about 20 minutes. And you generally won’t have any other symptoms besides the small hives where the tests were done, which go away within 30 minutes. If your prick skin tests are negative but your physician still suspects you might have allergies, more sensitive “intradermal” tests may be used in which a small amount of allergen is injected within the skin.

Skin tests are best performed in an allergist’s office to assure the test results are read properly and to minimize the risk of rare side effects.

Challenge Tests: A very small amount of an allergen is inhaled or taken by mouth. Challenges are done mostly with potential food or medication allergies. It is very important that they be supervised by a physician with specialized training and experience, such as an allergist.

Blood Tests: This test involves drawing blood, so results are not available as rapidly as with skin tests. IgE blood tests are generally used when skin tests might be unsafe or won’t work, such as if you are taking certain medications, or have a skin condition that may interfere with skin testing.

When to Proceed with Caution
There are methods of allergy testing that the American Academy of Allergy, Asthma & Immunology (AAAAI) believes are not useful, effective or may lead to inappropriate diagnosis and treatment. These include: allergy screening tests done in supermarkets or drug stores, home testing, applied kinesiology (allergy testing by testing muscle strength or weakness), cytotoxicity testing for food allergy, Rinkel skin titration method, provocative neutralization testing, Immunoglobulin G (IgG) testing for food allergy or sublingual provocation.

Healthy Tips
• Allergy testing by an allergist is a precise way to tell which, if any, allergens are contributing to your allergy symptoms.
• Once you know exactly what you are allergic to, you and your doctor will be able to develop a treatment plan to reduce or eliminate your allergy symptoms.

(from AAAAI.org Tips to Remember: Allergy Testing)